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MOTANUL
Joined: 19 Nov 2018
Posts: 214
Location: ROMANIA BUCHAREST
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Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
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 Posted: Mon Jul 15, 2019 3:56 am Post subject: |
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All the exhaust gaskets are simple to find. Just order new ones from a Porsche centre.
I have the smaller 944 turbo starter, and I cannot remove exhaust and wastegate without removing the starter. But I realised my current exhaust is mahoosive compared to the stock version.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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chuck21401
Joined: 20 Feb 2005
Posts: 526
Location: Annapolis, MD
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| Posted: Mon Jul 15, 2019 10:19 am Post subject: |
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| bureau13 wrote: | | So the starter thing is confirmed? |
Confirmed. Frees up a lot of room to work.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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chuck21401
Joined: 20 Feb 2005
Posts: 526
Location: Annapolis, MD
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| Posted: Thu Jul 18, 2019 2:43 am Post subject: Re: Replacing or refurbing wastegate (Tial, perhaps?) |
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| bureau13 wrote: | | I will very likely just buy a Tial |
Here is my question...how would one mount the TiAL? The stock 931 WG has the extra bracket on the "hat" that bolts to the car.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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bureau13
Joined: 07 Sep 2017
Posts: 480
Location: South Florida
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| Posted: Thu Jul 18, 2019 2:59 am Post subject: Re: Replacing or refurbing wastegate (Tial, perhaps?) |
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Good question. Supposedly, the Tial is considerably lighter...perhaps its light enough that it doesn't require the extra bracket? That does seem a little dodgy though...
| chuck21401 wrote: | | bureau13 wrote: | | I will very likely just buy a Tial |
Here is my question...how would one mount the TiAL? The stock 931 WG has the extra bracket on the "hat" that bolts to the car.
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_________________
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1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)
Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen) |
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Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
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| Posted: Thu Jul 18, 2019 5:24 am Post subject: |
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Will probably need spacers to mount on the stock exhaust. Will be smaller and lighter so no brackets will be required
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Mon Sep 30, 2019 4:20 am Post subject: |
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My favorite part about this thread is that the ebay seller is a former 'one of us' who moved on to a 930 from a 931
Engineer White.
I also bought one of his kits because it was cheap enough to not machine one myself but it isn't installed yet. Will post when I have it together. Wastegate was functioning but we had everything else out so why not go through it all
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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bureau13
Joined: 07 Sep 2017
Posts: 480
Location: South Florida
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| Posted: Sun Nov 03, 2019 2:53 pm Post subject: |
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So I removed the J-pipe and was basically looking to confirm my suspicious about the wastegate. I hooked up my air compressor to the hose that leads to the wastegate from the charge pipe, and the bottom "door" didn't budge. Also, I could hear what sounded like a LOT of air whooshing out somewhere, but it wasn't any place I could feel. It sounded like it was coming from above the wastegate. If the diaphragm is compromised, causing the door to not open, does that air exit via the top port? If so, that would make sense.
Also...how hard is that door to move? I tried pushing up on it and it didn't budge.
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)
Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen) |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Sun Nov 03, 2019 8:50 pm Post subject: |
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| bureau13 wrote: | If the diaphragm is compromised, causing the door to not open, does that air exit via the top port? If so, that would make sense.
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Yes!
| bureau13 wrote: |
Also...how hard is that door to move? I tried pushing up on it and it didn't budge. |
Pretty hard.. I don't think you are going to do it with your thumb, but no so strong that you can't disassemble/reassemble the spring by hand..
Maybe around 20 lbs to move the valve?
If the top of the diaphragm is about 2.5" for 5 sq inches and it should open at like 6 psi then 6X5=30 lbs to move the valve or compress the spring?
Just guessing..
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80 Turbo - Slightly Modified |
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chuck21401
Joined: 20 Feb 2005
Posts: 526
Location: Annapolis, MD
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| Posted: Mon Nov 04, 2019 3:53 am Post subject: |
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| bureau13 wrote: | So I removed the J-pipe and was basically looking to confirm my suspicious about the wastegate. I hooked up my air compressor to the hose that leads to the wastegate from the charge pipe, and the bottom "door" didn't budge. Also, I could hear what sounded like a LOT of air whooshing out somewhere, but it wasn't any place I could feel. It sounded like it was coming from above the wastegate. If the diaphragm is compromised, causing the door to not open, does that air exit via the top port? If so, that would make sense.
Also...how hard is that door to move? I tried pushing up on it and it didn't budge. |
Good idea to test it that way. The valve should move...it doesn't take much if it is working correctly. I posted this link on the other thread...a small handheld compressor will move the valve with 5-6 PSI. https://youtu.be/qg84Pz54Lqw
I agree, the air would exit via the top port.
When I had my WG on the bench I tried to push the valve up using two thumbs...didn't work so I gave up. I think it would be very difficult to do from under the car.
Unfortunately it sounds like you'll have to pull the WG and open it up to see what's going on in there. I got lucky, the WG diaphragm had simply come loose. I replaced the valve guide while I was in there. Who knows if it really needed to be done but the WG is working fine now.
I'm actually under my car again today....replacing the studs from the turbo to the exhaust and tightening everything back together.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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bureau13
Joined: 07 Sep 2017
Posts: 480
Location: South Florida
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| Posted: Mon Nov 04, 2019 12:51 pm Post subject: |
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Yeah, I'm not looking forward to pulling that thing out. I've heard it's pretty common to break the bolts, although everything came out easily with the j-pipe. I've been told I need to drop the starter and the exhaust, although it doesn't really look like it to me? Also, I know there's a bracket holding the top part of the wastegate in place, but I didn't see it. Not a lot of room in there...is it difficult to access those bolts? This sounds like a good candidate for borrowing my friends lift...
| chuck21401 wrote: | | bureau13 wrote: | So I removed the J-pipe and was basically looking to confirm my suspicious about the wastegate. I hooked up my air compressor to the hose that leads to the wastegate from the charge pipe, and the bottom "door" didn't budge. Also, I could hear what sounded like a LOT of air whooshing out somewhere, but it wasn't any place I could feel. It sounded like it was coming from above the wastegate. If the diaphragm is compromised, causing the door to not open, does that air exit via the top port? If so, that would make sense.
Also...how hard is that door to move? I tried pushing up on it and it didn't budge. |
Good idea to test it that way. The valve should move...it doesn't take much if it is working correctly. I posted this link on the other thread...a small handheld compressor will move the valve with 5-6 PSI. https://youtu.be/qg84Pz54Lqw
I agree, the air would exit via the top port.
When I had my WG on the bench I tried to push the valve up using two thumbs...didn't work so I gave up. I think it would be very difficult to do from under the car.
Unfortunately it sounds like you'll have to pull the WG and open it up to see what's going on in there. I got lucky, the WG diaphragm had simply come loose. I replaced the valve guide while I was in there. Who knows if it really needed to be done but the WG is working fine now.
I'm actually under my car again today....replacing the studs from the turbo to the exhaust and tightening everything back together. |
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)
Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen) |
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chuck21401
Joined: 20 Feb 2005
Posts: 526
Location: Annapolis, MD
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| Posted: Mon Nov 04, 2019 1:05 pm Post subject: |
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| bureau13 wrote: | | This sounds like a good candidate for borrowing my friends lift... |
A lift would be very helpful. My car is up on jack stands with ramps under the tires just in case. Not easy to work on the car this way...but doable.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler
Last edited by chuck21401 on Mon Nov 04, 2019 1:21 pm; edited 1 time in total |
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chuck21401
Joined: 20 Feb 2005
Posts: 526
Location: Annapolis, MD
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| Posted: Mon Nov 04, 2019 1:13 pm Post subject: |
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| bureau13 wrote: | | I've been told I need to drop the starter and the exhaust, although it doesn't really look like it to me? Also, I know there's a bracket holding the top part of the wastegate in place, but I didn't see it. |
The starter must be removed. I'm replacing the studs on the exhaust side of the turbo and was hoping to avoid removing the starter...but there is on bolt that connects the bypass pipe to the wastegate that isn't otherwise accessible.
So I had to pull that too. Luckily I didn't have to remove the J-pipe for the job I'm doing now. Be sure to remove the positive and negative wires from the battery...and put the car in neutral. You don't want to have the starter engage by mistake when reinstalling the wiring.
The bracket holding the wastegate in place is fairly accessible once everything else is out of the way. Here's a pic from when I was reinstalling the WG after fixing the diaphram and new valve guide. I left the U-clamp on the torque tube...only had to remove two bolts to get it out of there...not all 4.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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bureau13
Joined: 07 Sep 2017
Posts: 480
Location: South Florida
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| Posted: Thu Nov 28, 2019 1:33 am Post subject: |
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Here's a related but possibly odd question. So, for the wastegate to open, it requires both the boost from the control line and the exhaust backpressure to press hard enough to overcome the spring, right? Does anyone know what boost would be achieved if we remove the control line from the equation? In other words, if we solely rely on backpressure to open the wastegate, what be the boost limit?
No, I'm not planning on going with this type of setup, I'm just curious and doing some other experiments while awaiting a chance to change out or repair the wastegate diaphragm.
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)
Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen) |
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Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
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| Posted: Thu Nov 28, 2019 3:22 am Post subject: |
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All depends on the waste gate spring installed.......0.5, 0.7, 1.0 bar boost springs?? Needs boost line pressure to control the valve, not exhaust
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
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